The present invention relates to a blade driving assembly for an adjustable hair clipper and more particularly pertains blade driving assembly for driving the movable blade of a hair clipper to move laterally relative to the stationary blade in a reciprocating manner to cut the hairs and longitudinally to adjust the cut length of hairs.
Conventional hair clippers are usually provided with a movable blade driven by a blade driving assembly to reciprocate laterally relative to a stationary blade in an operative condition. The movable blade is fastened to a movable blade holder and the movable blade holder is provided with a fastening slot which engages with an eccentric pin driven by a motor to drive the movable blade holder and the movable blade to move in a lateral reciprocating manner. A torsion spring is usually provided to exert pressure upon the movable blade holder to bias the movable blade towards the stationary blade on one hand, and to control the movable blade holder to move forward or backward to adjust the cut length of hairs. The torsion spring is engaged with the movable blade holder by hooking the front ends of the torsion spring into respective recesses provided on the movable blade holder. When a user pushes the adjustment knob on the hair clipper forward, the torsion spring is driven to move forward and thereby driving the movable blade holder to move forward.
However, the use of torsion spring to drive the forward and backward movements of the movable blade holder makes it very difficult to achieve accurate adjustment of cut length of hairs. To achieve accurate adjustment of cut length of hairs, one possible way is to use high quality torsion springs with consistent tensility but such torsion springs are relatively expensive. Furthermore, torsion springs are easily susceptible to deformation, fatigue and other problems after prolonged usage, and so it would be difficult for conventional hair clippers to ensure accurate adjustment of the cut length of hairs after a period of time.